The present invention relates to a novel negative-working chemical-amplification photoresist composition or, more particularly, to a negative-working chemical-amplification photoresist composition capable of giving a finely patterned resist layer on a substrate surface having an excellently orthogonal cross sectional profile with high photosensitivity.
As is well known photoresist compositions used for forming a patterned resist layer in the manufacture of semiconductor devices and liquid-crystal display devices include positive-working photoresist compositions as a class giving a positively patterned resist layer by dissolving away the resist layer in the areas exposed to the light in the development treatment with a developer solution and negative-working photoresist compositions as the other class giving a negatively patterned resist layer by dissolving away the resist layer in the areas unexposed to the light in the development treatment. The negative-working chemical-amplification photoresist composition as the subject matter of the present invention is a negative-working photoresist compositions comprising an alkali-soluble resin, a compound capable of releasing an acid by the irradiation with actinic rays and a crosslinking agent for the resin.
In the photoresist composition of this type, the crosslinking reaction of the resinous ingredient is greatly promoted by the catalytic activity of the acid released from the radiation-sensitive acid-generating agent to give a high photosensitivity of patterning and a patterned resist layer of high pattern resolution can be obtained by development with an alkaline developer solution. By virtue of these advantages, the negative-working chemical-amplification photoresist compositions are now widely employed for patterning in the manufacture of semiconductor devices and liquid-crystal display devices.
Various kinds of compounds are known as the radiation-sensitive acid-generating agent used in the photoresist composition of this type including isocyanurate ester compounds such as tris(2,3-dibromopropyl) isocyanurate and the like disclosed in Japanese Patent Publication 8-3635.
This isocyanurate ester compound, which generates a halogenoacid when irradiated with the KrF excimer laser beam having a wavelength of 248 nm, is highly transparent to this laser beam to give a patterned resist layer having an excellently orthogonal cross sectional profile so that the compound is used in negative-working photoresist compositions for patterning with KrF excimer laser beams as well as in negative-working resist compositions for patterning by irradiation with electron beams and X-rays.
Along with the trend in recent years toward increasing compactness of various kinds of electronic instruments and increasingly high degree of integration in semiconductor devices, however, photoresist compositions are required to have a still higher sensitivity and to give a still improved resolution and the above mentioned negative-working chemical-amplification photoresist compositions formulated with the isocyanurate ester compound as the radiation-sensitive acid-generation agent can no longer comply with this requirement, in particular, in respect of the sensitivity. Accordingly, it is eagerly desired to develop a negative-working photoresist composition capable of exhibiting a high sensitivity even to the KrF excimer laser beam irradiation.
Japanese Patent Kokai 4-217249 discloses, as an acid-generating agent, use of diazomethane compounds such as bis(cyclohexylsulfonyl) diazomethane, bis(4-tert-butylphenyl-sulfonyl) diazomethane and the like in negative-working photoresist compositions. Though improved to some extent in the sensitivity, these photoresist compositions are still unsatisfactory in respect of the orthogonality of the cross sectional profile of the patterned resist layer obtained therefrom as compared with the photoresist compositions formulated with a halogenoacid-generating agent such as tris(2,3-dibromopropyl) isocyanurate and the like.
Further, Japanese Patent Kokai 8-292564 discloses a great variety of radiation-sensitive acid-generating compounds such as certain halogenoacid-generating compounds, bis(alkylsul-fonyl) diazomethanes and the like but nothing is suggested on the combined use of these acid-generating compounds in a specified proportion.
Besides, Japanese Patent Kokai 9-311451 discloses a negative-working photoresist composition containing a halogenoacid-generating compound and an onium salt-based acid generating compound in combination as the radiation-sensitive acid-generating agent but this photoresist composition has a disadvantage that, due to the unduly high acid strength of the acid released from the onium salt, the crosslinking reaction of the resinous ingredient is not limited to the exposed areas but extended to the areas unirradiated with the actinic rays not to give an excellently patterned resist layer.